Our present invention relates to a lamp holder and, more particularly, to a lamp holder specific to pin-based lamps, for example, compact fluorescent lamps with G 23, G 24 or 2G 11 type sockets and halogen lamps with G 12 or PG 12 type sockets and generally comprised of a housing of electrically insulating material having usually two contact springs whose bent shoulders engage detent recesses or projections on the lamp base so as to provide sufficient retaining force on the base and make an electrical connection with the pin thereof.
Lamp holders of this type serve on the one hand to make electrical connection between the conductors within the lamp and the electric current network supplying the lamp and, on the other hand, to retain the lamp mechanically in the holder. The lamps with which the invention is concerned are primarily those lamps which have detent formations in the lamp base, behind which the shoulder of the contact spring can engage, and contacts which are likewise engageable with the contact spring so as to provide the electrical connections.
Lamp holders of this type must have at least one contact spring for retaining the lamp base in position or to secure the lamp base against falling out of the lamp.
In a conventional lamp holder for the aforedescribed lamps and which represents the starting point for the present invention and over which the invention is an improvement, the contact spring is bent from a flat strip and has a hairpin shape with two shanks connected together through approximately a 180xc2x0 bend. The U-shaped member thus has a bight between a shank formed with the shoulder and constituting the base-retaining member and contact shank, and a bracing shank which resiliently engages a wall of the holder housing and urges the first-mentioned shank toward the lamp base.
This second shank, which may be referred to as a bracing shank, has an indexing formation formed therefrom and projecting outwardly to engage a formation on the housing behind which this indexing formation can lock. The contact spring is inserted with its U-shaped body into a pocket in the lamp housing in the same direction as the lamp is inserted and, when that contact spring is fully inserted, its detent engages behind the formation of the housing in a snap fit, thereby retaining the contact spring against tractive forces tending to pull it out of the housing. The detent can lie against the wall of the pocket inwardly of the projection and the shoulder on the lamp-retaining shank projects into the path of the lamp base to come into engagement with the latter, whereby that shoulder can be cammed outwardly by the base and spring behind the seat formed in the base for engagement thereof in the lamp holder.
Usually the lamp holder has two such pockets, each with a respective contact spring and the contact springs are disposed opposite one another to engage opposite sides of the lamp base. Of course it is also possible to use a single contact spring to retain the lamp base against a fixed abutment on the housing opposite that contact spring.
Lamp holders of the aforedescribed type have been found to be highly successful in practice.
However, it is always desirable to reduce the amount of material in such devices, to limit the work which goes into producing the unit and, of course, to limit the cost while maintaining the effectiveness of the lamp holder.
It is therefore the principal object of the present invention to provide an improved lamp holder, especially for the types of lamps mentioned earlier, whereby the contact spring can be simplified without reduction in its effectiveness and thus a considerable saving of material can be accomplished especially in the case of mass-produced lamp holders.
Another object of the invention is to provide an improved lamp holder which utilizes a simplified contact spring and which is therefore more desirable than earlier lamp holders for the same types of lamps.
Another object of this invention is to optimize the utilization of material in the fabrication of lamp holders.
These objects and others which will become apparent hereinafter are attained in a lamp holder configured to receive a base and, for example, conpact fluorescent lamps of types G 23, G 24 or 2G 11 or have halogen lamps of types G 12 or PG 12 and wherein the insulated housing receives at least one contact spring for retaining the lamp base and mechanically retaining the lamp base in the lamp shoulder housing or socket and wherein the shank of the contact spring provided with the shoulder is free from the aforementioned bight and is not connected to another shank bent from the contact spring via a bight, but rather the bracing shank is formed out of the shoulder forming the lamp-retaining shank and is provided directly with the indexing formation or lug. In other words the lamp-retaining shank has a free end and is generally flat except for a lug which is bent out of that shank between the end thereof and braces against the housing while directly forming the indexing lug, the shoulder and the lug projecting from opposite sides of the same shank.
More particularly, the lamp holder comprises:
a housing composed of electrically insulating material formed with a cavity opening along a side of the housing; and
at least one electrically conductive contact spring received in the housing for engagement with the base of the lamp for mechanical retention of the base and electrical connection therewith, the contact spring being formed from a planar metal strip with a shank having a free end lodged in the housing, a bend at an opposite end of the shank and forming a shoulder engageable with and biased against the base for retaining the base in the housing against tension tending to withdraw the base from the housing, and a barb formed from the shank between the free end and the shoulder and bent from the shank away from a direction in which the shoulder is bent from the shank for bracing against the housing, the barb being formed as a detent lug engaging behind a projection on the housing for retaining the contact spring in the housing.
The invention eliminates the need for a separate bracing shank bent from the retaining shank through 180xc2x0 and the function of that bracing shank is taken over completely by the lug which is bent out of the retaining shank between the ends thereof, this lug serving simultaneously as the indexing element for locking the contact spring in its pocket in the housing. The result is a significant saving of material for the contact springs without requiring a redimensioning of the housing or the balance of the lamp holder. In excess of one-half of the length of the sheet metal strip required for each contact spring is no longer necessary.
It has been found to be advantageous to cut out the barb or lug from the retaining shank so that it has a free end turned toward the end of the contact spring provided with the shoulder.
The contact spring itself can have a generally flat or planar shank from which the indexing lug or barb can be cut out and bent and which can be provided with the shoulder. The formation of the barb can be such that it itself is different from the lug formed on the bracing shank of the prior art contact spring bent through 180xc2x0 with respect to the retaining shank in that its free end is turned toward the shoulder rather than toward the free end of the metal strip opposite the shoulder. The barb can be elongated and connected to the retaining shank at an end of the barb turned away from the end of the contact spring provided with the shoulder and the barb can then have a straight portion including an acute angle with the shank and another portion at an obtuse angle of the straight portion and substantially parallel to the shank with the contact spring. Lodged in the housing this other portion can lie flat against the housing and can have an edge engaging the projection for locking the contact spring in the housing. The retaining shank has a portion extending from a junction of the barb with the shank to an end thereof and received in a slit in the housing.
With this shape and construction, the requisite bracing and locking function can be achieved without the bent shank extending the retaining shank.